If a set of attributes \(\mathbf {B} \subseteq \mathbf {X}\backslash \lbrace S\rbrace  \)  are descendants of \(S\) , \(\mathbb {E}[R(a,s^*)|\mathbf {x}_{t}]\)  is not identifiable. According to Proposition 2 in [1]}, we have that
\(\mathbb {E}[R(a,s^*)|\mathbf {x}_{t}] \le \sum _{\mathbf {I}} \frac{P(\mathbf {x}_{t,a},\mathbf {i})}{P(\mathbf {x}_{t,a})} \max _{\mathbf {b}} \lbrace  \mathbb {E}[R|s^{*},\mathbf {x}_{t,a}\backslash s_{t}, \mathbf {i}] \rbrace \) 
